/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.shardingsphere.infra.optimize.core.convert.converter.impl;

import org.apache.calcite.sql.SqlNode;
import org.apache.shardingsphere.infra.optimize.core.convert.converter.SqlNodeConverter;
import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.pagination.PaginationValueSegment;
import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.pagination.limit.LimitSegment;

import java.util.Optional;
import java.util.function.Function;

/**
 * Abstract limit sql node converter.
 */
public abstract class AbstractLimitSqlNodeConverter implements SqlNodeConverter<LimitSegment, SqlNode> {

    private Function<LimitSegment, Optional<PaginationValueSegment>> function;
    
    protected AbstractLimitSqlNodeConverter(final Function<LimitSegment, Optional<PaginationValueSegment>> function) {
        this.function = function;
    }
    
    @Override
    public final Optional<SqlNode> convert(final LimitSegment limit) {
        if (null == limit) {
            return Optional.empty();
        }
        Optional<PaginationValueSegment> paginationValue = function.apply(limit);
        if (!paginationValue.isPresent()) {
            return Optional.empty();
        }
        return new PaginationValueSqlConverter().convert(paginationValue.get());
    }
}
